Inhaled nitric oxide is commonly used to treat which condition?

• A. Persistent pulmonary hypertension of the newborn
• B. Neonatal sepsis
• C. Meconium aspiration without distress
• D. Transient tachypnea of the newborn

Answer: (A)

Inhaled nitric oxide is used when the problem is high pulmonary vascular resistance causing hypoxemia, as seen in persistent pulmonary hypertension of the newborn. Nitric oxide, delivered directly to the lungs, relaxes pulmonary vascular smooth muscle by increasing cGMP, which lowers pulmonary artery pressures and reduces right-to-left shunting across the foramen ovale and ductus arteriosus. This targeted vasodilation improves oxygenation without causing systemic hypotension because its effects are largely confined to the pulmonary vasculature.

Neonatal sepsis is treated with antibiotics and supportive care rather than vasodilators. Transient tachypnea of the newborn and meconium aspiration without associated pulmonary hypertension typically do not involve elevated pulmonary vascular resistance, so inhaled nitric oxide is not a standard therapy for those conditions. If meconium aspiration is accompanied by PPHN, iNO may be considered as part of the management, but its primary and most common use is for PPHN.